Doug Beghtel/The OregonianAn apple a day might not keep the allergist away.

My toddler loves apples. But apples don't love him back. Just about every time he eats one, he inevitably gags, coughs and finally hacks so hard that he throws up.

At first we figured he was choking on the peel or on big pieces. So we removed the peel and cut the apples into finer slices. But he kept barfing. Finally I started to wonder whether he was allergic to apples.

Moreno explained that there are two categories of allergies: food allergies and cross-reaction contact allergies, which can involve food. A child who has a cross-reaction allergy to a certain food may show symptoms such as swelling, redness, itchiness and tingling immediately after eating that food, she said. The child may also get a stomachache when the food comes into contact with the stomach lining.

Cross-reaction contact allergies include Oral Allergy Syndrome, which I'd learned about when I did an Internet search. Barrett said it's a cross-reaction to plant proteins: People usually react first to birch pollen; then, once they become sensitive to that, they can become sensitive to proteins in other plants, such as apples.

But while Barrett agreed that my son's symptoms sounded like Oral Allergy Syndrome, he said he's never heard of a 2-year-old with such a diagnosis, though he was quick to add, "There's always kids who do things that are unheard of."

It's possible, Barrett said, that what I'm seeing is just a food allergy to apples. But, he added, "apple is a very uncommon food to be a food allergen."

Barrett and Moreno differed on the best approach to my son's problem.

Barrett said he'd do a skin test with a raw apple. Typically, he said, skin tests are done with commercial extracts that have been sterilized, but they're not as effective as raw fruit. Barrett said it works like this: "You poke the apple with a needle, you poke the kid's skin with the needle and you poke a control person, like you or me." If the child shows a reaction and the control person doesn't, that's confirmation of an allergy.

But Moreno said she'd recommend holding off on a skin test for a very young child if the situation was not serious. "It's mostly just traumatic, having all the pricks done and not being able to process that," she said. "It just depends on how worried you are."

Instead, she suggested two solutions:

(1) Remove apples from my son's diet.

(2) Cook or microwave apple slices briefly before serving them. That's because the proteins in fruits break down quickly when exposed to heat. Because of that, Moreno said, she advises parents of babies who are starting on solids to avoid raw fruits and vegetables and instead use jar foods or cooked fruits and vegetables. (But raw nuts are less allergenic than roasted ones, Moreno said.)

Even as a child gets older and becomes able to cope with skin testing, Moreno said, it may still be easier for him or her to just avoid a troublesome food. The question is, she said, "How much is that food necessary for the culture of the family?"

Barrett also cautioned that skin tests must take into account the patient's health history. "The question is, does this make any sense with the patient," he said. When it comes to toddlers, he said, diagnosing an allergy is especially tricky because children are most sensitive to foods in the first few years of life. (A national study released last fall found that about 3 million U.S. kids are now affected by food allergies, an 18 percent increase since 1997, but Barrett said testing results in many false positives. On top of that, the study did not ask whether an allergy had been officially diagnosed by a doctor.)

At this point, I said to Barrett, "But this is the kid I nursed for 17 months -- I thought that was supposed to help avoid allergies!"

Barrett's reply: "You can sensitize your child, and they can develop a food allergy, through breast milk."

Which reminded me that I am allergic to grass pollen and made me wonder if I'd passed on that sensitivity. Moreno said, "People who have allergy symptoms with pollens are going to be more likely to have the food symptoms ... your child's probably going to inherit some of that."

But both Barrett and Moreno said that risk shouldn't stop moms with a family history of allergies from nursing. "Breast milk contains about a thousand other things that are beneficial to the child .. you don't want to rob the child of that," Barrett said.

For parents who have allergy questions, Moreno recommends this Web site: www.uptodate.com/patients, a medical resource site where you can search for information about allergies.

Does your child have a food allergy? What's your experience been like?